> I think the whole point of abstraction is to lessen complexity; wrap up many different things into one thing that's easy to reason about. Very few languages support creating good abstractions, unfortunately.
Abstraction lessens complexity, and also adds complexity.
Take monads in Haskell, for instance. Let's oversimplify and say that absolutely everything is done through monads. Great; we've now wrapped up many different things into one thing that's easy to reason about. And when I want to do something, I don't have to think at all - I just reach for a monad.
And then I have to think, because now I have to figure out how to make a monad do the specific thing that I actually want it to do.
Or I'm reading the code, and yes, that's a monad, because it always is, because everything's done through monads. But what is this monad at this location in the code actually doing? Well, I have to work my way back out of abstraction to concrete in order to understand that.
One way to think about this is abstract art. As art gets more and more abstract, at first I can't tell whether I'm looking at a blonde or a brunette. Then I can't tell whether I'm looking at a male or a female. Then I can't tell whether I'm looking at a human or a chair. And finally, I get to the point where I'm looking at a painting that could be anything, but it's impossible to say what it is. Abstraction has proceeded to the point that communication (between the artist and the viewer) has been lost. In the same way, abstraction in code can proceed to the point where communication between the author and reader is lost, and then it takes a lot of work to wade through the layers of abstraction to find out what the code is actually doing.